President Donald Trump tweeted Jan. 25, "I will be asking for a major investigation into voter fraud," but did not provide any evidence that such fraud existed. (Reuters)

President Trump’s call Wednesday morning for a “major investigation” into what he described as voter fraud was paired with a vow to potentially “strengthen up voting procedures.” Trump has repeatedly stated his belief that he lost the popular vote last year because of “millions” of illegal votes, although the things he described in a pair of early morning tweets focused instead on voter registration, including “those registered to vote in two states, those who are illegal” as well as “those registered to vote who are dead (and many for a long time).”

During a White House briefing on Tuesday, Sean Spicer, Trump’s press secretary, said that the president believed this because of “studies” that have been presented to him. At one point he cited a Pew study he said came out in 2008 that showed that “14 percent of people who have voted were not citizens.” Spicer was apparently conflating a couple of different studies, including research by Old Dominion University professors from 2008 and 2010 as well as a 2012 study released by Pew Center on the States, although neither of those supported what he was describing.

Trump has also invoked that Pew study before. The Pew study did find considerable problems with inaccurate voter registration, including dead people who remained listed on voter rolls and people who moved to new states and were listed on voter rolls in more than one place. However, the study “found no evidence that voter fraud resulted” from this, as David Becker, an elections expert who directed that Pew study, wrote on Twitter when Trump’s camp made similar comments in November.

Here are four other things you should know about claims of voter fraud and incorrect registration, according to Becker, who answered questions by email Wednesday:

1. No, the studies Spicer mentioned didn’t find what he said they did.

“Neither study he cites supports any findings of significant numbers of illegal ballots cast, and the Pew study I directed doesn’t address voter fraud at all,” wrote Becker, who is now executive director of the Center for Election Innovation and Research. “Every study that has looked at this has found only an infinitesimally small number of illegal votes nationwide.”

2. The Bush administration looked for voter fraud. They didn’t find all that much.

Under the second Bush administration, the Justice Department, where Becker worked until 2005 in the voting section, “brought their resources to bear to investigate and prosecute voter fraud last decade and only found about a handful of cases nationwide out of hundreds of millions of ballots cast,” he said. According to a New York Times report from 2007, the effort turned up essentially zero evidence of an organized attempt to sway federal elections, and many of the people charged misunderstood rules or filled out the wrong forms. (This effort to pursue voter fraud apparently played into another, larger scandal, though: dismissals of U.S. attorneys.)

Other efforts are undertaken to assess voting after it takes place, including some efforts by the secretaries of state who act as the chief election officials overseeing the actual voting process. (The group representing these officials nationwide, most of whom are Republicans, said in a statement Tuesday that they were “not aware of any evidence that supports the voter fraud claims made by President Trump.”)

In Ohio, Secretary of State Jon Husted is already in the middle of a review of the 2016 election there, following a similar review in 2012 that found just 135 potential voter-fraud cases out of more than 5.6 million votes cast. “Easy to vote, hard to cheat,” he wrote on Twitter early Wednesday in response to Trump.

3. People would “easily” find voter fraud at the scale Trump mentioned.

“Voter fraud at any scale even approaching the scale he’s talking about would be easily discovered, most likely before the election,” according to Becker. He pointed to several explanations, including that improper registrations wouldn’t match Social Security or Department of Motor Vehicles records.

4. “Unsubstantiated claims” can affect voter confidence.

Becker echoed the National Association of Secretaries of State in noting that Trump’s claims of massive voter fraud may wind up having one clear impact: Unnerving Americans who may believe these assertions. The group had pilloried what it called “unsubstantiated claims calling into question the systemic integrity of the election process” before the election, and it pointed back to that statement Tuesday.

Becker offered a similar view Wednesday, writing: “Many are very concerned about the effect of these unsubstantiated claims on voters confidence in our democracy, and the hard work that election professionals of both parties are doing to ensure that every vote counts, and that only those eligible can vote.”